One clarification - the stoic ratio is by mass, not volume. So one drop of fuel doesn't require 14.7 times the size of the fuel drop in terms of air. It requires much, MUCH more air than that. Remember that the air molecules are at a much greater distance to each other than the fuel molecules. Just to keep the science behind the experiment accurate.
Taken on a 175km trip now all looks good (touch wood) STFT around -1.6 Banks 1 and 2 LTFT around -7 Banks 1 and 2 and motor seems to be running smoother. Next I will check Fuel consumption Thanks for your help. Over here in Australia most of the mechanics I have spoken to about this problem just tell me to just reset the codes, this has made my head hurt for o many years, my fingers are crossed. Graeme in OZ
Mike- we just had a uplander in class with rich codes and intermittent hard start. FFV, alcohol content was reading 75% but actual content in fuel was less then 10%!
That's crazy, nice find Jake!!!!! Chevy seems to have an issue with this. Was this a sensor style or algorithim style alcohol content monitor? Actually in the next class we are going to be talking about measuring that content as part of the diag procedure. Mike Becker, Technical Services Instructor
I had a throttle body relearn done to fix the constant problem after cleaning it. I think I may have made a mistake I did a fuel composition reset using X431 on my 2011 5.3 flex fuel suburban , currently have e85 in my tank. Now I have 2 code errors p0171-00 and p0174-00 fuel trim lean system lean bank 1 and 2. Did I do something wrong? I would appreciate any help what to do and proceed. Thank you
Hi Ken, Your vehicle uses an algorithm to calculate fuel ethanol %. When you reset the fuel composition, it defaults to >10% ethanol. Since E85 burns at closer to a 10:1 ratio compared to Gasoline at 14.7:1 it will cause your vehicle to run lean and set those codes. The only way to fix this issue without measuring the ethanol content and re-programing the ECM. Is to run the tank empty and put in a tank of regular 10% or less ethanol in and do the fuel composition reset again. This way the ECM learned percentage will match the fuel in the tank. Unless you manually drain the tank, you may have to do this twice to get the % back to normal. Hope this helps, Thanks Ryan W, Technical Instructor
I have this problem since two months now, which literally drives me crazy! About the symptoms: Very noticeable jerking, stuttering and starting difficulties when the engine is warm/hot. Sometimes the engine won't even start at all. Engine has starting-problems. The problem only occurs after the engine has warmed up and ONLY when starting/idling. Error only occurs after about 10-15 minutes after the car has been shut down. ISTA says P0172: system too rich; which means that the DME either detects too little air or too much gasoline. So to reproduce the problem: 1. Car start perfectly when cold, not a single problem or vibration! 2. I drive half an hour normally (City/motorway) 3. Shutting the car off. 4. Waiting 15 - 20 minutes 5. Restarting the engine 6. Either the car starts with huge difficulties (sputters, shakes, jerks) OR it stalls and shuts off immediately. So far I've replaced: Intake manifold gaskets. (Even though this can't be the cause of the issue, since in the event of an air leak the DME would detect too much air and not too little (or am I wrong there?) 6x injectors 6x spark plugs 6x ignition coils MAF 2 O2-sensors 2 MAP sensors Air Filter Engine oil change (with filter) 2 Camshaft Positioning sensors Cleaned both Vanos-Selenoid Crankshaft Positioning sensor I'm struggling to understand why an intake leak would cause a rich mixture?!ISTA says I have to check the Intake system... (I already checked 3 times!, although without a smoke-tester) Wouldn't an air leak cause a lean condition since unmeasured air enters the engine? OR The ECU demands more fuel because there's an intake leak. In other words; since there is unexpectedly more air in the system, the DME has to spray more fuel to compensate the unmeasured air; hence "system too rich"? Therefore the ECU recognised that more fuel is sprayed into the engine as usual and because of this the DME says: system too rich? ----------------------------------- Intake leak = More (unmeasured) air requires more fuel to be sprayed into the engine to compensate the "unknown" air, therefore "system too rich" --> Because the DME has to put more fuel then normal? OR Intake leak = More (unmeasured) air requires more fuel to be sprayed into the engine to compensate the "unknown" air, therefore "system too lean"? --> Because there is more air then normal? Am I losing the plot here? Both make sense, but which one is scientifically and physically right? I'm desperate and on the verge of a mental breakdown
@@GoTechTraining Please I really need your help. Nobody is able to help me. Not even the dealership It seems like gas is getting into the oil pan. I changed the oil, and it ran fine for 3 days. Then stalling issues again. Have you had a chance to think about it? Or do you offer something like a TeamViewer function? Thank you
Also for the vehicle to be running rich, you could be getting blow by and the air gathering up oil and taking it through a failed crank case vent or pcv into the intake whereby it would be burnt and making the exhaust rich.
Hey James, you're absolutely correct. Oil could end up in the intake manifold and cause the engine to run right. Nice! Mike Becker, Technical Services Instructor
Blackbox is ecu. New stuff to learn for old timer.I ask my kids if I have trouble with my pc. Lol. I wondered how my bike starts without choke, now I know.I have to watch more of your vids. Great stuff.
Hello I hope you're doing well just would like to have an idea why the hose that goes from the canister purge valve in the Gasquet it would shrink when accelerating i would really appreciate it thanks
Graeme in OZ UPDATE !!!!!!!!! This weekend may have found my issue, while checking PCV valve I noticed there was a small rubber pipe connected to the valve cover then led to PCV valve the push on connection was very easy to pull apart so I installed small hose clamp to secure it. I then connected my newly acquired Foxwell NT301 OBD2 Engine Fault Code Reader Scanner and found the instrument gave me a green tick indication when connected where as before it was an orange triangle (Yellow indicates there's an issue that has been solved). The Short Term Fuel Trim readings now look better showing around -2 banks 1 & 2 LTFT is about -9 but from what I've read this takes time to adjust after problem is resolved. Will need to take her for a few drives to see if I have solved the 13 Year issue !!!!!!!!. Graeme in OZ
Hey Graeme, that's awesome!!!! Yeh, LTFT will take a little time to come back to normal. Sounds like you just might have it fixed :) Mike Becker, Senior Technical Instructor
Hello. 2003 Mitsubishi 3.8L V-6, 220,000 trouble free miles. Fuel economy is where it should be. LTFT 1&2 are +12.5% at hot idle. But goes to 0% and stays there when revved to 2,500 rpm. STFT 1&2 are 0% at hot idle. When extra fuel is sprayed on identified leak of intake manifold (leaking o-ring, I used smoke to find) the STFT immediately goes to -6 and then returns when the extra fuel is burned off. Could this intake air leak thats affecting both banks cause the truck to go into a limp mode, giving me these codes? P0335 P2135 P0340 Also, why does LTFT go to 0% when under load? Thanks!
HI, The intake leak will not effect cam and crank signals or cause the vehicle to go into limp mode. There must be another issue with the system. With a intake leak fuel trims go down under load for a few reasons. First under load the engine consumes a much larger volume of air, so the air leak affects the fuel trims much less. Also when the engine is at 2500 RPM the throttle body is open causing the pressure in the intake to be close to atmospheric pressure, which means no vacuum in the Intake. With no vacuum in the intake it will not be able to suck as much unmetered air into the engine. Ryan Wilsing, Technical Instructor
@@GoTechTraining thank you very much! That makes sense about the LTFT. I will check out the throttle position sensor as it seems to go back to normal when it cools down for 15+ minutes. Maybe it is overheating. Maybe I can replicate issue by getting TPS hotter with a hair dryer. Thanks again!
Do you have a suggestion for this? My VW Golf TSI 2008 (BLG engine code) has a Fuel System Too Rich error. When the exhaust emissions are measured at idle all is fine, but at 2500 rpm the carbon monoxide is way too high. So the car failed inspection today. The error code is actually not present at the moment. I deleted it months ago and it didn't come back. So I forgot about it until I was reminded about it today due to the failed inspection. The error code was P0172
Hey J Wester, a rich condition is a lack of oxygen in the exhaust. It's interesting that it's only under load and not at idle. I'd take a close look at the air fuel ratio sensor and the 02 sensor. Try forcing the car rich and lean and see if the sensors respond appropriatly. Mike Becker, Senior Instructor
@@GoTechTraining Thank you for your answer. This engine seems to be using an 02 sensor. Initially I was looking for the MAP Sensor. In this engine the sensor is an intake manifold pressure sensor combined with intake air temperature sensor. As I understand the computer uses these two values to calculate the air mass and adjusts the air/fuel mixture
My 2001 vw beetle glx 1.8t..had PO172.. Cleaned the airflow sensor and throttle body..Runs like brand new now..As a mechanic for 32 years in Audi Bmw Mercedes I recommend cleaning the airflow sensor every oil change..at 2000 miles..Thank You and I approve this message...
I have a P0175 code system to rich bank 2. I took it to Autozone and their computer indicates to change the fuel injector. How do I know which one or do I have to change them all?
Hello Armando, There is no way their computer could tell you, that you have a faulty fuel injector by just reading a code. What year, make, and model do you have? What are all the codes set? ~Ryan
@@GoTechTraining it’s a 2013 Silverado with 200k miles. I cleaned the MAF, but now I’m thinking maybe I should just clean the throttle body and get new spark plugs. I don’t remember doing that anytime soon. It’s been a great truck and haven’t done anything to it other than just general maintenance.
Is it a flex fuel vehicle ? If so it is very common for the fuel alcohol % level to become skewed. It can be as easy as reseting it with a scan tool. It’s a special function called fuel composition reset ~Ryan
Hey Jeff, actually in this class we do not. We get to fixing it in one of the future classes. This class is intended to talk about how the fuel trim system works. Each week we build on this until it's time for the repair. Here is a link to that class! ua-cam.com/video/BlcWBZ-iaTY/v-deo.html Mike Becker, Technical Services Instructor
Awesome! Thanks for that. You've helped me learn so much in just a couple hours. I've Been playing your vids as I work and the way you've presented information has been so easy to follow.
Thats awesome to hear Jeff! Thanks! Glad we are helping you learn. Our next class will air live this Thursday 5/4/17. We go live at 11am and 2pm central time. You can win a hat or t-shirt from us if you are there and properly answer the question. I hope to see you there! Mike Becker, Technical Services Instructor
Wouldn't a vacuum leak affect both banks on a two bank engine excluding a Manifold leak on on one bank? Same on a bad injection or bad plug or coil pack on that bank?
I have a P0171 lean code for a Corolla 2001 with 197k miles. My Long Fuel Trims are 40.1 %. Could that be that i have a clogged fuel injector? I cleanned my MAF sensor, change my O2 sensors, change All Gaskets. Still have the code ON. Any advise would be great...
Hi William, likely a bad catalytic convertor is the cause of the trouble code but is the cat getting killed by something else? Is the truck running rich/lean or burning any oil? ~Mike
Hi, thank you for getting back to me about the code well I don’t think it’s burning oil I don’t think it’s running rich or running lean some times it take a couple more turns to start I replaced the map sensor the truck runs good it has 250 k maybe it is the Cat I was going to replace the bank 1 o2 sensor the last one at the bottom of pipe . Do you think it’s the catalytic under the truck the one under truck maybe it restricted giving False reading
I have a 1998 mercedes c230 with a P0170(running rich). I swapped out the maf sensor bc it looked like the easy answer. I have a cracked air filter housing will this be the source of my issue? Next would be to clean inspect my throttle body. After that im going to change my fuel filter and injectors. Car was in and out of storage so it may be rusted injectors? P0170 is the only code present.
The crack on the air box housing is actually a pipe going towards the grill before the air filter. Im also missing a clamp on the air box but it still appears to be well sealed.
Hey Danh Nguye, if the crack is prior to MAF sensor then no, it will not cause your issue... can you force the engine to run lean by pulling a vacuum hose? I'd like to confirm the 02 sensor is able to switch from rich to lean. Mike Becker, Senior Technical Instructor
I have a 06 VW beetle 2.5l. I have a p0171 code. Did a smoke test and no vacuum leak was detected. Car is running rough on idle and reading short term 25% and long term 20%. I changed the maf back in July and it was running great until now. No maf code or anything when it started to have problems. I was told to replace the 02 sensors. Please help.
Hey Ulices, sounds like you're dealing with a rich condition. First step would be to look at the fuel trims using a scan tool and see what is actually occouring. Mike Becker, Senior Instructor
My 03 F150 Lariat 5.4 keeps giving me a P0401 code and negative trims around -12 to -16. I have replaced EGR valve, DPFE sensor (and hoses), EGR tube, EGR vaccum solenoid, IAC valve, plugs, coils, intake manifold, fuel injectors, and EVAP purge solenoid...
I have a 03 dodge ram 1500 4.7 and have bank 1 to Rich replace the injectors and fuel regulator and both 02 sensor's n the map sensor but it still idles rough to where it almost dies the truck doesn't have EGR valve
Hey Floyd, are the injectors good quality or Ebay specials? I've heard of cheapy injectors causing issues. Can you force it lean? Mike Becker, Senior Technical Instructor
I just found your site. I am new to this and it is very interesting subject. i just bought a new Altel 808 and it amazing to watch it on live data. I have a 1999 gmc k2500 5.7 I have replaced the injection spider and cleaned the carbon out of the intake. I Have changed the o2 sensors and it is telling me that i have a low heater out put on bank 1 sensor bank 2. I have looked at the wiring and it looks good. any ideas. The A/F is 14.7. o2;s are reading 450. The engine is high mileage, does not use any oil, the compression is 160 to 165. starts good and runs great. Thanks
Hi I have a 2000 honda accord 2.3L and it over heated so bad I had the Spark plug wires melted on the Spark plug so I fixed all that and replace my spark plugs and wires and I replaced the thermostat and now the car won't turn on unless I step on the gas alil so I connect a OBD REAMER to it and the codes it brings up is cylinder 2 misfire and cylinder 4 misfire and car running rich what can be the problem? Thanks
Hey Pete, overheating is never a good thing. You could have a headgasket/cylinder head issue causing your concern. I'd start by checking compression. Mike Becker, Senior Instructor
I had P0172 and P0175 codes on my 2013 GMC Sierra 2500hd. Once I pulled everything up on the computer, I noticed my fuel alcohol content was @ 64%. I reset that and got rid of my rich codes. Now I have a P0300 code and O2 sensor codes for both upstream sensors. Fuel trims are perfect. What could be my issue? I'm planning to check for fouled plugs and maybe bad coils but I thought it was weird I didn't have any misfires codes until after I reset the FAC and trim levels back to zero. Also all 4 O2 sensors are brand new and operate in range.
Hi I recently cleaned the throttle body and changed intake manifold gasket and put in a new maf sensor. Now I’m pulling a RICH code for bank 2 what would be the first things to check?
myslecinaczej I used a smoke test and diagnosed the vacuum leak at manifold gasket, I don’t have access to old maf sensor but the Rich code is only pulling on bank 2
@@hunterbartausky7432 Vacuum leak always generate a lean code and not a rich one. Leaking injector (misfire?) and the lambda itself (does it deliver a clean sine signal?) Let us know what it was once you figure it out.
Hey Hunter, like myslecinaczej said, a vacuum leak will cause it to run lean, not rich. We are looking for something else. What kind of car is this? Year/make/model/engine size? Mike Becker, Senior Instructor
Hey Randal, you want to verify the heater circuit is getting power and ground. You can confirm it by putting a test light across the heater circuit and see if it lights up when the car is started. ~Mike
I have an old school truck a 89 s10 pickup with a 2.5 liter engine and a manual transmission. I have replaced everything but the tps and map sensor. New exhaust including the cat. New gas tank and fuel pump. Odd thing with this truck is it hates fuel pumps. Person I purchased truck from also replaced the fuel pump and hanger assembly. I live near Harrisburg Pa and I can drive for about 15 minutes and the truck runs fine. It's like a switch was hit and the truck starts to run like crap. When I put my foot on clutch the engine almost stalls. Sometimes it does. The engine shakes violently and I almost didn't make it home today. How does the engine go from running great to running like crap? I wish you could give the ecm a error. I have a snap on red brick. I got codes 23 22 13 34 and 32. Before I left this morning I unplugged the o2 sensor hoping to keep it in open loop. The only thing I don't understand on the red brick is the spark count and block learn and interrogater. I know the o2 sensor works and it's not lazy. What is causing this? The way they engineer stuff is why I don't do this professionally any more. The stupid stuff engineers come up with. Don't know how you deal with their stupidity!
Hey, sorry you're running into such big issues with your truck! Have you checked you system for rust? Maybe you have some rust in the fuel rail that's plugging up injectors? Mike Becker, Senior Technical Instructor
Hi Guys i got a 2009 Audi A4 B8 1.8tfsi with a P0172 code that doesn't seem to go away, i have replaced the lambda sensor, water pump and thermostat (Car was leaking coolant) all four fuel injectors, the MAF sensor works fine, Sometimes the car has a hard start even when i have driven for quite a while, occasionally i smell petrol on start up while driving and the smell disappears shortly while driving, a compression test was also done which was Ok, would appreciate your input on this, car is in Kenya
Hey Anthony, smelling fuel and showing a rich code could definitely be related. Are you able to watch the fuel pressure after the car is shut off? It should remain steady. If it's dropping, maybe it's leaking into the cylinder. Are you certain your new injectors are "good" injectors? Mike Becker, Senior Technical Instructor
@@GoTechTraining I'm from Jamaica and I have a 2011 A4 B8 1.8 tfsi with P0172 & P0420 and was rebuilt after factory fault oil consumption issue. It also idles ruff at cold start, it's fine after heats up and drives for a bit. I will check the FRP if it drops when engine shuts off. But with all the oil issues it had previously, I think the intake manifold & for sure the cat needs cleaning (cat may need replacing). I also think I got 02 sensor bank 1 code some time ago, cleaned it and the code went. But it's long term rich at -18. I've cleaned MAF, IAT & throttle body as well. I sprayed a bit of sean foam in the o2 sensor port, the P0420 code went & OBD change cat from failed to pass, and the fuel trims had went down to 0. But after a bit, went to -18, short term first and then now long term So, could this rich condition, also be due to clogged cat?
Hey, so being that you messed with the cat a bit and it changed it could be related. The engine needs to be able to efficiently exhale. If it can't it'll code. Yes, its plausible that a plugged cat could cause your issues. Mike Becker, Senior Technical Instructor
Very good video with a lot of helpful information . Thank you. Quick question, My car recently was running lean 21 percent lean long trim and 18 short trim on bank 2 due to a exhaust leak between the 2 flanges right before the cat. I got that fixed and now the car sometimes runs -18 but mostly stays on -6 to -12 range on short trim and bounces from -10 to 3 on long trim. How many driving cycles does it take for it to adjust to normal .So far I drove the car 3 times
My question about the Lambda reading on a scan tool is , for an example, 1.2 on your lambda chart on your video training, when you read this value on a scan tool , is the computer on your car taking fuel away because the fuel trims rich ? If someone can answer the question I would be thankful!
CEL TOO RICH TO LEAN AND MISFIRES. I changed maf sensor n air filters. Light still on Then Changed all Fuel injectors light still on. Changed all spark plugs and all oxygens sensors light still popped back on. What could this be please help! I’m tired of fixing stuff that probably wasn’t the answer. Last hope was the oxygen sensors once they were out they were fried bad . Once I clear the codes rev up and drive it handles fine. But once sitting idled it sputters
I've have learn a lot from watching this video thanks guys Just one question. My car was running lean on bank 2 due to a vacuum leak. 21 short term and 16 long term during idle Well I got that fixed and now its running rich each time I accelerate. Like sometimes 8- to 13- on the long trim and 5 to 8- on short trim. The fuel trims are okay during idle Is there anything I missed? or is it normal for the car to run very rich while accelerating it.
I have a question i have a 2013 kia rio. LTFT is at +30 and STFT is 0. I checked for vacuum leaks and have none. Oxygen sensor reacts to fuel being sprayed into intake. I bypassed fuel system with terra clean machine and no change in trims. my question is could carbon on the intake valves cause this much fuel trim correction? this is a GDI engine.
I also wanted to add that raising the rpm while monitoring the fuel trims decreases the LTFT numbers down to about +20 and to me that indicates a vacuum leak, but no vacuum leak was found by spraying intake with brake clean. PCV is good too.
Christian, have you checked the air intake snorkel for tears? Also, how is the MAF sensor? The valves would need to be really bad to cause this extreme of a case. My feeling is that you have an improper measurement of air. Either not being read correctly or air sneaking in after the MAF. Mike Becker, Senior Technical Instructor
Thanks for getting back to me Mike, this car doesn't have a MAF sensor it uses a Map sensor. I checked the Map sensor voltage and was sitting at 1.5v and I didn't see that as a problem.
Juergen, yes you're right. It is in frames not seconds, I misspoke. Sorry about that! Thanks for correcting it! Mike Becker, Technical Services Instructor
I have 2010 impala with p0171, at first it starts fine but after running after 20 minutes the engine starts sputtering and dont go over 10mph. Im not sure what it could be. Any help?
I need y’all‘s help I have a 97 Toyota forerunner 3.4 L that I’m having a major Rich issue and every time I try something it does not work. I have replaced my O2 sensors, engine coolant temperature sensor, injectors, mass airflow sensor, fuel pressure sensor and about to change my fuel pressure regulator,fuel filter all vacuum lines as well as PCV valve, throttle position sensor. I got a new IAT but the vacuum tube on it fell off so I put the old one back on. I’ve done a compression test and all are within spec new spark plugs and coils and have swap the wires out with some wires that I had from before just to see if the ones that were on it are bad. The plugs are the dual tipped plugs that are recommended. There is a colder intake on the system which has been working fine on it for the past five years. All my fuses and relays check out yeT I am still getting a -20 something for my short term -17ish for my long-term. I get a misfire cylinder one error code but when I look at cylinder one misfire Count is less than 10 in the span of an hour. If I hit the throttle short term will zero out for a few seconds and then slowly Drop back to -20. When the engine is cool and I start it the mass air will be pulling close to 10 psi but after it Gets done with its warm-up cycle it drops down to around 3 sometimes even 2 1/2 psi. My injection it’s so low that the car almost stalls out somewhere in the upper 2gpm area. And when I first start the vehicle after it cooling down for a while it takes a long time to start. Somebody help me please
What if a a vehicle briefly goes to Open Loop - Drive on deceleration only till it stops? Truck is at normal operating temperature. But it stays in Closed Loop the remaining time. 2012 Toyota Tundra 5.7 240,000 miles
GoTech there’s been no codes just intermittently being a startup at operating temperature where it goes straight to idle at 550rpm approx, most times it goes to like 900 and drops to idle which is normal. I’d also been noticing the mpg is getting lower. Idle began to become rough at stops randomly, not to a stall point. I looked at the maf it was dirty cleaned it and mpg got better then It began to tank. I could watch the fuel needle move as I drove say 50 miles and by 90 I consumed 1/4 tank, usually I’m about 120 miles for that. I have had a scanner on it for a week as I drive watching fuel trims B1 LT is about 5.0 at idle and 2.7 as I drive, ST changes is quickly but is near 2 at idle and -0.8 some times near 1.5 as I drive . B2 LT 3.0 at idle and nearly the same as B1 as I drive. ST is nearly 0 at idle and goes up to -2.0 as I drive. These numbers were far worse with the bad maf, pushing ST 10 on both banks and dropping to -1.0 as I drove. I’m still thinking that there’s a leak some where but the break cleaner test around the hoses and intake manifold showed no leak. My Evap canister was replaced, all new from Toyota. 10k miles ago. Replaced the rattling gas cap as the fuel trim numbers got better, closer to 0 at idle B1 and B2 at idle hover between 0 and 3.7 at idle LT. Bank 1 tending to be the higher. And I eventually replaced the purge solenoid on the engine for not holding vacuum. And the numbers have been the same but are getting better, including the mpg. Maybe near 14mpg avg for my 150 mile day, as opposed to 11 or 12. Sorry for the thesis here, but I’ve been analyzing this for a week now and it wasn’t till everything above was done that it did the OL- Drive thing. Maybe it’s a strategy like you say, a Toyota thing.
I have a p2098 bank 2 code on a Dodge Challenger 3.6L it’s running a lean fuel trim. What could my issue be? I’ve changed all O2 sensors and catalytic converters and still jerks a bit and had a check engine light. I added a fuel injector cleaner LUCAS and it removed my check engine light for 40 miles then it came back???
Eric, i'd start by monitoring the fuel trims. When does it run lean, idle, under load? This would then lead to the next steps, looking for vacuum leaks, fuel issues, etc. Mike Becker, Senior Technical Instructor
P0171 basically means you have a vacuum leak usually the first place I go to the gas cap to make sure it was tightened properly because if it is not then you're going to show a vacuum leak.
Hey David, thanks for watching. So a vacuum leak can set a P0171 but there's also a ton of other things. Also, the gas cap is more likely to set an EVAP code like P0440 or something before setting a lean code. Mike Becker, Senior Instructor
I've got a Ford Focus 1.6 petrol 2006 mark 2. It's long term fuel is minus 10. It's long term negative numbers have been slowly been going more and more negative. There is no engine light on and seems to run OK. Where do you suggest looking? Thanks :)
John, when your trims are going negative that means your engine is running rich. Verify fuel pressure first off. See if you can force the engine lean to see if the O2 is responding. Mike Becker, Senior Technical Instructor
My 2010 Chevy malibu I have the po172 code engine will nit start the oil has gas in it the MAP sensor checked out ok any ideas that would make bank 1 rich
Very useful information sir thank you Sir I have Chevy suburban 2007 and I'm getting codes p0172 and p0175 system too rich on both banks and ratio is showing short fuel trim at 0 and long fuel trim at -25 what do you suggest me to do first
Thank you for watching A Rahman! On your suburban, these were very common to run into fuel composition calculation issues. There should be a PID on your scanner saying ethanol content. Verify that seems right. if you are running standard pump gas we usually look for 5-10%. Anything higher than that can give you issues. Ethanol requires higher fuel volume which could be exactly why your truck is running rich. Mike Becker, Senior Technical Instructor
Very informative. Thanks for the taking the time. You teach a great class. Your step by step process is unmatched. Thanks for passing the knowledge to us all.
I have a Lexus is350 showing p2238, I have replaced the O2 sensor the dtc does not go away. After checking the fuel trims I have 0 on both on short fuel trim but on the long fuel trims they are -3 and -6, any idea about what is causing it?
Plz help me.... Don't understand trim but help... My k20 civic si... Burn rich but no code ... Run poor and but runs better when low on fuel... I cleaned maf and map senors and throttle body and nothing help plz.... Also when the car is real cold it starts at a low idle then jumps to below 2000 rpm
You have to find what's causing it to run rich. Are you able to force the car lean? Is the purge solenoid stuck open all the time? Mike Becker, Senior Technical Instructor
@@GoTechTraining what's the purge solenoid.... I am sorry I Jus trying every thing..... Gonna try and clean the pvc valve and the air assist control valve... Maybe it's not getting enough air....?? But the air to fuel is jus all over the place
The Purge solenoid is the solenoid that connects eventually to the vapor canister. Your best bet on here may be to take this thing into a shop for a diagnosis. Mike Becker, Senior Technical Instructor
@@GoTechTraining did..... But realise u gave me the best idea than any other mechanic here.... These problems I am having more seem to be as u say the evap system or the canister.... Gonna take them down and check them... But how can I test the solenoid or jus get a new one????? Please and thank you... U have been a great help
Question I replaced the intake manifold gasket and Throttlebody gasket and replaced the egr valve and evap and still getting a lean code what can it be
I have 2004 mini cooper 1.6l r50 check engine light on and code p2097 post catalyst fuel trim system too rich bank1 what should I do? somebody said I should change a oxygen sensor... but which one should I one on the hood or one under bottom of the car?
I have a 1996 F250 5.8. It only has 116k miles on it and the engine sounded really good until a few weeks ago when I put about 2 year old gas in it. I KNOW THAT WAS STUPID. it was about 10 gallons. The very next day, it was rough starting up but it ran fine once it started, however, the next day, the truck was shaking, started sounding like it was misfiring, and whatever. I didnt siphon out the bad gas, instead I out fresh gas in. The fixes I have done on it thus far are: fuel filter, cleaned injectors, spark plugs and wires, new distributor cap and rotor. and it still isnt running right. I took it to a DIY mechanic who has been a mechanic for probably 50 years and he said it sounds like the lifters. What do you make of it?
Do you think that the gas is a coincidence? I find it hard to believe adding old gas caused it to ruin lifters that were fine before. I don't buy it. I would inspect fuel trims. Maybe your gas had water in it and the truck is running lean to the point of misfiring. Not sure on that lifter idea man. I'd do some testing before jumping to engine work on a truck that sounded good. Mike Becker, Senior Technical Instructor
I didnt think so either. My dad had said he didnt believe old gas would be the culprit, but the water content may have the engine running lean. Thank you so much. Ill take this info and work accordingly. You the man. SUBSCRIBED!
Old gas can cause an engine to run poorly. You could try adding some of that water eliminator to the tank. See if it helps, it shouldn't hurt anything. Thanks for subbing man! Mike Becker, Senior Technical Instructor
Eric, that P2096 is a lean code of sorts. You need to inspect the vehicle for a lean condition. Maybe it has something to do with an air leak before the post cat o2 sensor. Mike Becker, Senior Technical Instructor
I have a 2002 Dodge Neon SE, P0172 code with 160,000 miles. No vacuum leaks, new plugs, new map sensor, new IAC, new O2, and new injectors. Still have the code after reset. Can you guys help? I`m ready to push my daily driver off a cliff. Fuel trims are pegged at -25. codes were reset after each part was replaced. Car will not pass Pa. inspection with MIL on.
My car is a 02 chevy prizim. I keep getting a po 420 cat system low efficiency code. I have already replaced the following. The upper and lower purge solenoid was replaced, Replaced the charcoal canister, changed the up and down stream 02 sensor. I replaced the mass air flow sensor. I replaced the cat. I also checked all the evap hoses and their is no leaks. I also changed all the spark plugs and pick up coils. I'm at my witts end and trying to figure out. Why it keeps giving this code. And keep blowing the cat, purge solenoids and pick up coil. I also did a smoke test and it well sealed.
Hi great lesson, my LTFT is at 0% since I checked a few months ago, does that mean my trims are really good? my STFT go's from -6% to +6 and bounces up and down between the two . is that a good thing ?
Hey 337 Thanks. Yeh that sounds good. Your short terms will bounce, that's normal. +/- 6 sounds pretty average. Long terms at 0 is what's really nice. Means the car seems to be dialed in! Mike Becker, Technical Services Instructor
Wells Vehicle Electronics thanks for the reply, 20 year old honda civic b16a sir2 engine, stock , I'm happy with that answer just shows how well made them engines are. Thanks for the reply and love your videos.
Long Term is the window of time the adaptive memory dictates the fuel trim, Short Term is live data calculating to learn the parameters for the adaptive memory to update the Long Term. The O2 sensor signals lean below .45 volts & rich above .45. The Engine Controller only cares about that threshold & uses that to determine fuel trim. .. in other words the computer calculates the % of time that the O2 sensor is past the threshold of .45 volts & does that each time the threshold is crossed.
Hey, thanks for the video. Very helpful. My shogun sport v6 has codes P0170 and P0173, both fuel trims. It seems to be running fine except a slight change in idling speed every minute or so (from 1000 to 700ish RPM). The previous owner has changed an o2 sensor (top of cat) but the 'check engine light' is back on. I've unplugged the MAF sensor and the idling speed increases, then goes back to normal once plugged back in. That's all I've done so far. Any ideas appreciated! Bit of a head scratcher 🤔
Hey Mark, Do you have a scan tool that can watch data? I'd like to see what the fuel trims are reading at idle and at a moderate load. There are a lot of possibilities to what could cause this issue. Mike Becker, Senior Technical Instructor
@@GoTechTraining thanks Mike, yes I have the torque light obd2 thing I'll take some screenshots and send them to you if you like? There's 4 sensors per bank, I'll try and get them on the same screen. What's your email?
So I'm so confused 2005 PT cruiser replaced 2 02 sensor P0031 and P0037 OH2S) both low voltage ( FL0007 EE18 BL01 threw this at one point as well but I think it's cleared couldn't find what this meant) people are telling me that mean it's running lean so it's a vacuum leak... I'm freaking I tried replacing the PCV valve thinking it may be clogged... still save codes could a leak in the exhaust be ducking sir all is brand new but I'm wondering it the bolts aren't tightened enough the guy that was under there last had an issue tightening a bolt. I've been up 2 weeks solid 3 in the morning trying to learn and figure it out!
Kathy, if both 02 sensors are reading low voltage and they've been replaced then you have only a few things it could be. Could be air leaks in the exhaust before the sensors, a severely lean running engine, a wiring issue from 02 to PCM or a PCM issue. My next test would involve feeding the engine some sort of fuel, probably propane, to see if I could get the 02 sensors to show rich. This tells me the sensor works, the wiring is ok, and the PCM is ok. if I richen the engine and I get no reaction in the data...then I have a sensor, wiring, or PCM issue. That make sense? Mike Becker, Senior Technical Instructor
@@GoTechTraining Thank you so much I've Been telling the mechanics around here that but they look at me like I have 4 heads I have to find someone that can understand this concept because I don't have a heck of alot of testing equipment. ...it's hard in the Albany, NY area. I understand it could also be an oil leak it the Oil pressure switch is leaking it could act like a vacuum leak as well s this correct? Or a purge Solenoid I already replaced the PCV valve. Thank you so much I greatly appreciate it !
Kathy, not sure how an oil pressure switch could cause this issue. A bad purge solenoid could though if it were stuck wide open. Mike Becker, Senior Technical Instructor
@@GoTechTraining I just read somewhere how touch the system is if something is working incorrectly sends a signal back to CPU (EPC or EMC) it will reduce voltage how crazy they made it this sensitive
Can y'all do some post carb, pre obd2 fuel trim videos PLEASE!? Reading blinking lights sucks! Do u have insight? My issue on a poor random idling 92 Nissan MT KA24E KC XE no CEL per Nissan. I'm sick of it becoming this parts cannon.. still have all original parts on hand.
So I got a po191, po171, po174..I replaced MAF, Throttle body, fuel rail sensor and fuel pump module on my 2005 f150 v8 3v...what is the solution. I have loss of power under load ...I am tired of throwing. MONEY at it...
Fantastic lecture! A connected topic: anybody knows how to deactivate learning procedure on a flex fuelcar (volvo in this case) . Thre is no ethanol content sensor but computer leatns thru the Lambda readings and injection pulse duration ...causing many problems when driving regular fuel. I am tired iwth them so simply would love to deactivate the process but there is no obvious way to do so. I can only reset the content to the default value of 50%. Then the crap learns and sometimes rich 70% with the engine to be floode on a cold start. Ideas?
Thank you very much! That seems crazy that the car would "learn" such a high ethanol count with no ethanol in the fuel..what's it truly learning? Are you sure you don't have something wrong causing it to read so rich? I've seem the algorithms get stuck, GM especially, but after resetting they are usually ok again. Is there maybe a software re-flash for the car or something? Mike Becker, Senior Technical Instructor
@@GoTechTraining I missed your reply! Thanks. There is a counter for ethanol content and each time you fill the tank the learning algorithm is initiated. It learns thru the lambda and injections timing. Therefore if there is something wrong with with fuel to sir ratio it interprets it as alternate fuel percentage in the tank and store ty he ethanol content reading. Next time you want to start in cold conditions it ask long injection time to account for ethanol and the engine is flooded. And I have a bi-directional tool so I am able to reset the content to the default (50% !) value. So yes, apparently there is something wrong but it is do tough to find out with this intelligence involved 😂. Would love to deactivate it first but have no idea how. Thinking about replacing the ECU for similar engine one but not accommodated as the flex fuel.
Hi can someone answer my question I have 07 ford f150 5.4 it has 171 code I put mass sensor and02 sensor on but it read long term 99.2 bank 1 sensor2 please help
You may have a vacuum leak, some times you can hear the leak. If you can't find it you may need to smoke your engine to find it. ALSO Exhaust leak before o2sensors 1. Good luck I'm sure you will fix it 😊
I have a p0172 code, running rich. Only went on when there was a cold snap and engine light went off when weather warmed up. By cold I mean -30c then warming to -6c. Could a sensor freeze?
Hello I own a 2005 Crossfire I have codes Chrysler with code P0172 and P0175 > I have had problems I also code P0239 Air induction blower failed but I hear it running at start up. I am a senior citizen and can't afford to take it to a shop if I could find one my next thing is take it off the rd Most shops do not want to work on this car since it is a Bastard car neither Mercedes or Chrysler or individual shops will not touch this car. It has a Mercedes engine 3.2 Liter V6 . I replaced all injectors and plugs wires and and individual coils the car runs great but as soon as I get close to the emission station it throws the P0172 and P0175. I looked for loose vacume hoses and I found one and I fixed that. My car is due in February and I don't know what I can do get this to pass emission. In a few years the car is exempt emission if I use Historic tags. I don't drive car much but the emissions will not allow me to go through the test for a week. Like I said the car runs great but soon as I get close to emission station it throws codes. I drove it for a week and today it did same thing 3 times in a row I went to the emission station. How frustrating.
hi, i,m new subscriber, great video! my car is nissan skyline 300gt 2002 year. lambda is 1,017, but CO is very high 1,57-1,76. what is possible causes? thanks!
Hey M.Night207, what kind of pressure regulator are we talking about? The old school vacuum diaphragm one? If that's the one, then ya, generally speaking it will be leaking if it fails. Mike Becker, Senior Technical Instructor
I got a question so I have a 2003 Ford Mustang 3.8 v6 and my LTFT B1 and B2 are both at -99.5 but no codes at all and engine seems to be running fine what’s going on with it?
Hey KComputers, curious, what are you STFT when the LTFT is -10.3? Are they hovering 0? A -10 trim shows you are running slightly rich. What kind of car is this on? Mike Becker, Senior Technical Instructor
to anyone watching this in the future and notices the audio is off, a way to get around this is 2 have two youtube tabs open of this video, one to watch on mute, and another to have audio playing and minimized. the time difference is ~9:40 seconds. so fast forward one to that time mark and then hit play on both of them as quickly as you can. was driving me crazy.
So if my 03 Toyota Corolla S is giving me P0420 and p0446 and p0440 and p0171. Should I replace both o2. The car has like 350000 miles lol so I’m guessing everything is old or shot and needs to be replace... thank u
Hey Mike, I'm 52 years old and knows nothing about the tech side of a car...been watching your videos, if I don't understand I'll rewind for second and third viewing, but I'm learning so much from you. Just brought a scanner (Autel MOT Pro, is this good scanner?) and playing with it and understanding it more because of your teachings....you are doing a great job, minus the cough. If I could give you 10 thumbs up I would.
Hey John, yeh i was a little bit sick in this video. Glad we are helping you learn. Means a lot to us! That's a good starter tool. Get's you some codes, and some info. There will always be room to grow in tools if you really get into this. Thanks for watching! Mike Becker, Technical Services Instructor
I have a car that can run on petrol and on LPG. When run on petrol I get HO2S 0.3V, stuck lean. When run on LPG, I get HO2S 0.7V stuck rich. Also HO2S is brand new and OEM. Using OBD reader,HO2S voltage is constant, it is not moving from rich to lean. Any idea what to look for?
Manifold issues could definitely cause a vehicle to change the fuel trims. If the cracks are drawing air in then I would expect the engine to go lean, not rich. Mike Becker, Senior Technical Instructor
so if my 97 ram 1500 5,9L came with 1 pin hole injectors and i upgrade to 4pin hole injectors im gonna be running richer but if the PCM can trim enough like 12-15% negative i should be okay and no CEL?
Hey Joey, if you're changing the flow rate of the injectors you'll need to program the PCM. It will likely set a code and not properly fuel. Mike Becker, Senior Instructor
Very informative video. I have a p0301 and my car have a rough idle after a warm up. During the initial rough idle when the car start I notice my STFTspike up to -20% and LTFT 0% and go back to normal. My car also hesitates or loses power between 2.5k to 3k rpm. What you think the possible issue ?
Hi Wendy, honestly there could be 1000 different things causing your issue. Your P0301 means your computer is recording misfires on cylinder 1. The misfire could be causing the fuel trim spike, or the fuel trim spike could be causing the misfire. What kind of car, miles, maintenance record? Need a lot more information to be able to get you any sort of accurate idea.Thanks! Mike Becker, Technical Services Instructor
Wells Vehicle Electronics Im driving a Subaru 07 wrx turbo 160k miles. Car has always been stock and no modifications other than cold air intake ( never have any issues after installation). I've replaced from spark plugs and coils. New OEM o2 and maf sensor replaced due to needed for placement. For the maintenance and condition of this car I have always service myself. I like to do preventative maintenance so everything up to par. Now I'm stump where I should look. Thank you.
Wendy, sounds like you really enjoy keeping your car nice. So, it seems you have replaced many parts already that I would have suggested at maintenance. That's good! So we have 2 clues here, P0301 and a rich condition at initial starting of the car. I would put a fuel pressure gauge on it at this point. Monitor the pressure when the key is turned off. It should hold. I am thinking you have a partially stuck open injector that is leaking fuel into the cylinder. This can cause a rough idle that clears up. Also, have you been adding coolant at all? These motors are known for head gasket issues, is it possible your engine's leaking coolant into cylinder 1 when it sits, then burns it off at start up? Does cylinder 1's spark plug look different than the other 4? Mike Becker, Technical Services Instructor
Wells Vehicle Electronics, the spark plugs have similar wear nothing noticeable difference. I gapped the spark plugs to specs at .030. I swap the coils and spark plugs and also the injectors between cylinder 1 and 4. I did a fuel injector clean individually by modifying a spray carb and choke cleaner with a 9 volt battery. And the spray seem to be fine with similar stream. There are no after leaks after the spray. I'm changing the o ring for all the injectors since I notice slight deterioration. But I have not test the fuel pressure since I don't have the tester. How is it possible that I have a vacuum leak by seeing short term fuel trim and long fuel trim ? And also my 02 sensor for bank one is 2.9 volts and fluctuated between 2.8 with very little voltage variation ( this before the cat converter.) but my post cat converter fluctuate between 200mV and 800mV. My car symptom is rough idle at warm up, and my car also hesitates at 2.5k rpm in every gears. With my pedal to the floor my car won't pick up speed until the rpm slowly pass 2.5k rpm.
Your fuel trims are showing a rich condition. The fact that your short terms go negative means the PCM is taking fuel away, not adding like it would for a vacuum leak. The front sensor on there is probably a wideband a/f ratio sensor. The voltage will probably sit right around there. Watch our wideband class, I go in depth into them in there. You have done all the checks I can suggest over the internet. At this point I would want to look at live data on a scan tool and see if anything sticks out. It may be time to find a really good diagnostic shop and take it there :( Mike Becker, Technical Services Instructor
One clarification - the stoic ratio is by mass, not volume. So one drop of fuel doesn't require 14.7 times the size of the fuel drop in terms of air. It requires much, MUCH more air than that. Remember that the air molecules are at a much greater distance to each other than the fuel molecules. Just to keep the science behind the experiment accurate.
Taken on a 175km trip now all looks good (touch wood) STFT around -1.6 Banks 1 and 2
LTFT around -7 Banks 1 and 2 and motor seems to be running smoother. Next I will check Fuel consumption Thanks for your help. Over here in Australia most of the mechanics I have spoken to about this problem just tell me to just reset the codes, this has made my head hurt for o many years, my fingers are crossed.
Graeme in OZ
My fingers are crossed for you too, Graeme Redman!
Mike Becker, Senior Technical Instructor
Mike- we just had a uplander in class with rich codes and intermittent hard start. FFV, alcohol content was reading 75% but actual content in fuel was less then 10%!
That's crazy, nice find Jake!!!!! Chevy seems to have an issue with this. Was this a sensor style or algorithim style alcohol content monitor? Actually in the next class we are going to be talking about measuring that content as part of the diag procedure.
Mike Becker, Technical Services Instructor
I had a throttle body relearn done to fix the constant problem after cleaning it. I think I may have made a mistake I did a fuel composition reset using X431 on my 2011 5.3 flex fuel suburban , currently have e85 in my tank. Now I have 2 code errors p0171-00 and p0174-00 fuel trim lean system lean bank 1 and 2. Did I do something wrong? I would appreciate any help what to do and proceed. Thank you
Hi Ken,
Your vehicle uses an algorithm to calculate fuel ethanol %. When you reset the fuel composition, it defaults to >10% ethanol. Since E85 burns at closer to a 10:1 ratio compared to Gasoline at 14.7:1 it will cause your vehicle to run lean and set those codes. The only way to fix this issue without measuring the ethanol content and re-programing the ECM. Is to run the tank empty and put in a tank of regular 10% or less ethanol in and do the fuel composition reset again. This way the ECM learned percentage will match the fuel in the tank. Unless you manually drain the tank, you may have to do this twice to get the % back to normal. Hope this helps, Thanks
Ryan W, Technical Instructor
I have this problem since two months now, which literally drives me crazy!
About the symptoms:
Very noticeable jerking, stuttering and starting difficulties when the engine is warm/hot. Sometimes the engine won't even start at all. Engine has starting-problems.
The problem only occurs after the engine has warmed up and ONLY when starting/idling.
Error only occurs after about 10-15 minutes after the car has been shut down.
ISTA says P0172: system too rich; which means that the DME either detects too little air or too much gasoline.
So to reproduce the problem:
1. Car start perfectly when cold, not a single problem or vibration!
2. I drive half an hour normally (City/motorway)
3. Shutting the car off.
4. Waiting 15 - 20 minutes
5. Restarting the engine
6. Either the car starts with huge difficulties (sputters, shakes, jerks) OR it stalls and shuts off immediately.
So far I've replaced:
Intake manifold gaskets. (Even though this can't be the cause of the issue, since in the event of an air leak the DME would detect too much air and not too little (or am I wrong there?)
6x injectors
6x spark plugs
6x ignition coils
MAF
2 O2-sensors
2 MAP sensors
Air Filter
Engine oil change (with filter)
2 Camshaft Positioning sensors
Cleaned both Vanos-Selenoid
Crankshaft Positioning sensor
I'm struggling to understand why an intake leak would cause a rich mixture?!ISTA says I have to check the Intake system...
(I already checked 3 times!, although without a smoke-tester)
Wouldn't an air leak cause a lean condition since unmeasured air enters the engine?
OR
The ECU demands more fuel because there's an intake leak. In other words; since there is unexpectedly more air in the system, the DME has to spray more fuel to compensate the unmeasured air; hence "system too rich"? Therefore the ECU recognised that more fuel is sprayed into the engine as usual and because of this the DME says: system too rich?
-----------------------------------
Intake leak = More (unmeasured) air requires more fuel to be sprayed into the engine to compensate the "unknown" air, therefore "system too rich" --> Because the DME has to put more fuel then normal?
OR
Intake leak = More (unmeasured) air requires more fuel to be sprayed into the engine to compensate the "unknown" air, therefore "system too lean"? --> Because there is more air then normal?
Am I losing the plot here? Both make sense, but which one is scientifically and physically right?
I'm desperate and on the verge of a mental breakdown
What kind of car are you working on?
Mike Becker, Senior Instructor
GoTech
2012 BMW F10 535i xDrive 109.000 km. Check my video. I captured the problem
ua-cam.com/video/lBPZEJDPXTw/v-deo.html
@@GoTechTraining Please I really need your help. Nobody is able to help me. Not even the dealership
It seems like gas is getting into the oil pan.
I changed the oil, and it ran fine for 3 days. Then stalling issues again.
Have you had a chance to think about it?
Or do you offer something like a TeamViewer function?
Thank you
@@Italiano9091 if your gas is mixing with oil it could be the high pressure fuel pump.
Also for the vehicle to be running rich, you could be getting blow by and the air gathering up oil and taking it through a failed crank case vent or pcv into the intake whereby it would be burnt and making the exhaust rich.
Hey James, you're absolutely correct. Oil could end up in the intake manifold and cause the engine to run right. Nice!
Mike Becker, Technical Services Instructor
Awesome video my 2005 mercedes e320 had a lean code what I fund is missed placed snorkle i clear the code I hope everything is fine now thank you
Awesome, gotta love an easy fix!
Mike Becker, Senior Instructor
Blackbox is ecu. New stuff to learn for old timer.I ask my kids if I have trouble with my pc. Lol. I wondered how my bike starts without choke, now I know.I have to watch more of your vids. Great stuff.
Hey Denis! I'm glad you're catching on and educating yourself! Any questions, don't hesitate.
Mike Becker, Senior Technical Instructor
hi from vegas really love the way you explain things on the fuel trim made me look at diag from a whole different view thanks
Hello I hope you're doing well just would like to have an idea why the hose that goes from the canister purge valve in the Gasquet it would shrink when accelerating i would really appreciate it thanks
Had an envoy with a p0171 an a p0496 p0300 with long term at 35+. missing an intake vac line cap an purge valve was stuck open still checked the maf.
Hey Daniel, sounds like that thing had a bunch of issues. Got it all fixed up now?
Mike Becker, Technical Services Instructor
Graeme in OZ
UPDATE !!!!!!!!!
This weekend may have found my issue, while checking PCV valve I noticed there was a small rubber pipe connected to the valve cover then led to PCV valve the push on connection was very easy to pull apart so I installed small hose clamp to secure it. I then connected my newly acquired Foxwell NT301 OBD2 Engine Fault Code Reader Scanner and found the instrument gave me a green tick indication when connected where as before it was an orange triangle (Yellow indicates there's an issue that has been solved). The Short Term Fuel Trim readings now look better showing around -2 banks 1 & 2 LTFT is about -9 but from what I've read this takes time to adjust after problem is resolved.
Will need to take her for a few drives to see if I have solved the 13 Year issue !!!!!!!!.
Graeme in OZ
Hey Graeme, that's awesome!!!! Yeh, LTFT will take a little time to come back to normal. Sounds like you just might have it fixed :)
Mike Becker, Senior Technical Instructor
Hello. 2003 Mitsubishi 3.8L V-6, 220,000 trouble free miles. Fuel economy is where it should be.
LTFT 1&2 are +12.5% at hot idle. But goes to 0% and stays there when revved to 2,500 rpm.
STFT 1&2 are 0% at hot idle. When extra fuel is sprayed on identified leak of intake manifold (leaking o-ring, I used smoke to find) the STFT immediately goes to -6 and then returns when the extra fuel is burned off.
Could this intake air leak thats affecting both banks cause the truck to go into a limp mode, giving me these codes?
P0335
P2135
P0340
Also, why does LTFT go to 0% when under load? Thanks!
HI,
The intake leak will not effect cam and crank signals or cause the vehicle to go into limp mode. There must be another issue with the system.
With a intake leak fuel trims go down under load for a few reasons. First under load the engine consumes a much larger volume of air, so the air leak affects the fuel trims much less. Also when the engine is at 2500 RPM the throttle body is open causing the pressure in the intake to be close to atmospheric pressure, which means no vacuum in the Intake. With no vacuum in the intake it will not be able to suck as much unmetered air into the engine.
Ryan Wilsing, Technical Instructor
@@GoTechTraining thank you very much! That makes sense about the LTFT.
I will check out the throttle position sensor as it seems to go back to normal when it cools down for 15+ minutes. Maybe it is overheating. Maybe I can replicate issue by getting TPS hotter with a hair dryer. Thanks again!
Do you have a suggestion for this? My VW Golf TSI 2008 (BLG engine code) has a Fuel System Too Rich error. When the exhaust emissions are measured at idle all is fine, but at 2500 rpm the carbon monoxide is way too high. So the car failed inspection today. The error code is actually not present at the moment. I deleted it months ago and it didn't come back. So I forgot about it until I was reminded about it today due to the failed inspection. The error code was P0172
Hey J Wester, a rich condition is a lack of oxygen in the exhaust. It's interesting that it's only under load and not at idle. I'd take a close look at the air fuel ratio sensor and the 02 sensor. Try forcing the car rich and lean and see if the sensors respond appropriatly.
Mike Becker, Senior Instructor
@@GoTechTraining Thank you for your answer. This engine seems to be using an 02 sensor. Initially I was looking for the MAP Sensor. In this engine the sensor is an intake manifold pressure sensor combined with intake air temperature sensor. As I understand the computer uses these two values to calculate the air mass and adjusts the air/fuel mixture
Gracias maestro. Veo sus videos en español pero en inglés un poco. Gracias nuevamente por su aporte a la enseñanza
My 2001 vw beetle glx 1.8t..had PO172..
Cleaned the airflow sensor and throttle body..Runs like brand new now..As a mechanic for 32 years in Audi Bmw Mercedes I recommend cleaning the airflow sensor every oil change..at 2000 miles..Thank You and I approve this message...
Thanks for sharing
I have a P0175 code system to rich bank 2. I took it to Autozone and their computer indicates to change the fuel injector. How do I know which one or do I have to change them all?
Hello Armando,
There is no way their computer could tell you, that you have a faulty fuel injector by just reading a code.
What year, make, and model do you have? What are all the codes set?
~Ryan
@@GoTechTraining it’s a 2013 Silverado with 200k miles. I cleaned the MAF, but now I’m thinking maybe I should just clean the throttle body and get new spark plugs. I don’t remember doing that anytime soon. It’s been a great truck and haven’t done anything to it other than just general maintenance.
Is it a flex fuel vehicle ? If so it is very common for the fuel alcohol % level to become skewed. It can be as easy as reseting it with a scan tool. It’s a special function called fuel composition reset
~Ryan
@@GoTechTraining yes it is. Do I need to take it in to have that done? Is it easy to do ?
Not quite done the clip but do you provide information on the repair needs for that car?
Hey Jeff, actually in this class we do not. We get to fixing it in one of the future classes. This class is intended to talk about how the fuel trim system works. Each week we build on this until it's time for the repair. Here is a link to that class! ua-cam.com/video/BlcWBZ-iaTY/v-deo.html
Mike Becker, Technical Services Instructor
Awesome! Thanks for that.
You've helped me learn so much in just a couple hours. I've Been playing your vids as I work and the way you've presented information has been so easy to follow.
Thats awesome to hear Jeff! Thanks! Glad we are helping you learn. Our next class will air live this Thursday 5/4/17. We go live at 11am and 2pm central time. You can win a hat or t-shirt from us if you are there and properly answer the question. I hope to see you there!
Mike Becker, Technical Services Instructor
Wouldn't a vacuum leak affect both banks on a two bank engine excluding a Manifold leak on on one bank? Same on a bad injection or bad plug or coil pack on that bank?
South Main Auto sent me to see your class, Great program, I need lots of this and will follow more videos.
Awesome John! Thanks!
Mike Becker, Senior Technical Instructor
I have a P0171 lean code for a Corolla 2001 with 197k miles. My Long Fuel Trims are 40.1 %. Could that be that i have a clogged fuel injector? I cleanned my MAF sensor, change my O2 sensors, change All Gaskets. Still have the code ON. Any advise would be great...
Sounds like it's running very lean Jose. Sure, it's possible it's an injector issue.
Mike Becker, Senior Instructor
Hi greetings.. what would cause P0420 on 2006 Honda Ridgeline Rtl any advice?
Hi William, likely a bad catalytic convertor is the cause of the trouble code but is the cat getting killed by something else? Is the truck running rich/lean or burning any oil?
~Mike
Hi, thank you for getting back to me about the code well I don’t think it’s burning oil I don’t think it’s running rich or running lean some times it take a couple more turns to start I replaced the map sensor the truck runs good it has 250 k maybe it is the Cat I was going to replace the bank 1 o2 sensor the last one at the bottom of pipe . Do you think it’s the catalytic under the truck the one under truck maybe it restricted giving False reading
I have a 1998 mercedes c230 with a P0170(running rich). I swapped out the maf sensor bc it looked like the easy answer. I have a cracked air filter housing will this be the source of my issue? Next would be to clean inspect my throttle body. After that im going to change my fuel filter and injectors. Car was in and out of storage so it may be rusted injectors? P0170 is the only code present.
The crack on the air box housing is actually a pipe going towards the grill before the air filter. Im also missing a clamp on the air box but it still appears to be well sealed.
Any suggestions?
Hey Danh Nguye, if the crack is prior to MAF sensor then no, it will not cause your issue... can you force the engine to run lean by pulling a vacuum hose? I'd like to confirm the 02 sensor is able to switch from rich to lean.
Mike Becker, Senior Technical Instructor
my LTFT stuck at 2.38 positive on idle as well on acceleration what does that means ?
Hello,
If it is 2.38% LT FT, that should be in a normal range and is not something to worry about.
Do you have any trouble codes stored?
~Ryan
@@GoTechTraining no trouble code but before my mileage is 15 km per littre but now 11 km
I have a 06 VW beetle 2.5l. I have a p0171 code. Did a smoke test and no vacuum leak was detected. Car is running rough on idle and reading short term 25% and long term 20%. I changed the maf back in July and it was running great until now. No maf code or anything when it started to have problems. I was told to replace the 02 sensors. Please help.
Is it possible your MAF went bad again? How does it react under WOT?
Mike Becker, Senior Technical Instructor
I have a 1998 Honda Accord and two codes came up, P0170 and P0172, where can I start because it’s a little it confusing?
Hey Ulices, sounds like you're dealing with a rich condition. First step would be to look at the fuel trims using a scan tool and see what is actually occouring.
Mike Becker, Senior Instructor
@@GoTechTraining would you happen to know where they would be located at? Sorry lol
My 03 F150 Lariat 5.4 keeps giving me a P0401 code and negative trims around -12 to -16. I have replaced EGR valve, DPFE sensor (and hoses), EGR tube, EGR vaccum solenoid, IAC valve, plugs, coils, intake manifold, fuel injectors, and EVAP purge solenoid...
I have a 03 dodge ram 1500 4.7 and have bank 1 to Rich replace the injectors and fuel regulator and both 02 sensor's n the map sensor but it still idles rough to where it almost dies the truck doesn't have EGR valve
Hey Floyd, are the injectors good quality or Ebay specials? I've heard of cheapy injectors causing issues. Can you force it lean?
Mike Becker, Senior Technical Instructor
@@GoTechTraining I bought them on Amazon and they have 4 holes instead of factory's no I can't
I just found your site. I am new to this and it is very interesting subject. i just bought a new Altel 808 and it amazing to watch it on live data. I have a 1999 gmc k2500 5.7 I have replaced the injection spider and cleaned the carbon out of the intake. I Have changed the o2 sensors and it is telling me that i have a low heater out put on bank 1 sensor bank 2. I have looked at the wiring and it looks good. any ideas. The A/F is 14.7. o2;s are reading 450. The engine is high mileage, does not use any oil, the compression is 160 to 165. starts good and runs great. Thanks
Hi I have a 2000 honda accord 2.3L and it over heated so bad I had the Spark plug wires melted on the Spark plug so I fixed all that and replace my spark plugs and wires and I replaced the thermostat and now the car won't turn on unless I step on the gas alil so I connect a OBD REAMER to it and the codes it brings up is cylinder 2 misfire and cylinder 4 misfire and car running rich what can be the problem? Thanks
Hey Pete, overheating is never a good thing. You could have a headgasket/cylinder head issue causing your concern. I'd start by checking compression.
Mike Becker, Senior Instructor
I had P0172 and P0175 codes on my 2013 GMC Sierra 2500hd. Once I pulled everything up on the computer, I noticed my fuel alcohol content was @ 64%. I reset that and got rid of my rich codes. Now I have a P0300 code and O2 sensor codes for both upstream sensors. Fuel trims are perfect. What could be my issue? I'm planning to check for fouled plugs and maybe bad coils but I thought it was weird I didn't have any misfires codes until after I reset the FAC and trim levels back to zero. Also all 4 O2 sensors are brand new and operate in range.
Hi I recently cleaned the throttle body and changed intake manifold gasket and put in a new maf sensor. Now I’m pulling a RICH code for bank 2 what would be the first things to check?
STFT and LTFT between both banks. Replacing parts based on guessing is not best idea.
Is it easy to instal the old MAF in place of the old one?
myslecinaczej I used a smoke test and diagnosed the vacuum leak at manifold gasket, I don’t have access to old maf sensor but the Rich code is only pulling on bank 2
@@hunterbartausky7432 Vacuum leak always generate a lean code and not a rich one.
Leaking injector (misfire?) and the lambda itself (does it deliver a clean sine signal?)
Let us know what it was once you figure it out.
Hey Hunter, like myslecinaczej said, a vacuum leak will cause it to run lean, not rich. We are looking for something else. What kind of car is this? Year/make/model/engine size?
Mike Becker, Senior Instructor
GoTech 1999 new body Silverado with 5.3
P0141 replace my downstream 2xs OEM 2.4 eclipse
Bad parts? What else can cause it
Hey Randal, you want to verify the heater circuit is getting power and ground. You can confirm it by putting a test light across the heater circuit and see if it lights up when the car is started.
~Mike
Whats a good scanner for seeing runing rich on both banks .06 4runner 4.7
I have an old school truck a 89 s10 pickup with a 2.5 liter engine and a manual transmission. I have replaced everything but the tps and map sensor. New exhaust including the cat. New gas tank and fuel pump. Odd thing with this truck is it hates fuel pumps. Person I purchased truck from also replaced the fuel pump and hanger assembly. I live near Harrisburg Pa and I can drive for about 15 minutes and the truck runs fine. It's like a switch was hit and the truck starts to run like crap. When I put my foot on clutch the engine almost stalls. Sometimes it does. The engine shakes violently and I almost didn't make it home today. How does the engine go from running great to running like crap? I wish you could give the ecm a error. I have a snap on red brick. I got codes 23 22 13 34 and 32. Before I left this morning I unplugged the o2 sensor hoping to keep it in open loop. The only thing I don't understand on the red brick is the spark count and block learn and interrogater. I know the o2 sensor works and it's not lazy. What is causing this? The way they engineer stuff is why I don't do this professionally any more. The stupid stuff engineers come up with. Don't know how you deal with their stupidity!
Hey, sorry you're running into such big issues with your truck! Have you checked you system for rust? Maybe you have some rust in the fuel rail that's plugging up injectors?
Mike Becker, Senior Technical Instructor
Hi Guys i got a 2009 Audi A4 B8 1.8tfsi with a P0172 code that doesn't seem to go away, i have replaced the lambda sensor, water pump and thermostat (Car was leaking coolant) all four fuel injectors, the MAF sensor works fine, Sometimes the car has a hard start even when i have driven for quite a while, occasionally i smell petrol on start up while driving and the smell disappears shortly while driving, a compression test was also done which was Ok, would appreciate your input on this, car is in Kenya
Hey Anthony, smelling fuel and showing a rich code could definitely be related. Are you able to watch the fuel pressure after the car is shut off? It should remain steady. If it's dropping, maybe it's leaking into the cylinder. Are you certain your new injectors are "good" injectors?
Mike Becker, Senior Technical Instructor
@@GoTechTraining I'm from Jamaica and I have a 2011 A4 B8 1.8 tfsi with P0172 & P0420 and was rebuilt after factory fault oil consumption issue. It also idles ruff at cold start, it's fine after heats up and drives for a bit. I will check the FRP if it drops when engine shuts off. But with all the oil issues it had previously, I think the intake manifold & for sure the cat needs cleaning (cat may need replacing). I also think I got 02 sensor bank 1 code some time ago, cleaned it and the code went. But it's long term rich at -18. I've cleaned MAF, IAT & throttle body as well. I sprayed a bit of sean foam in the o2 sensor port, the P0420 code went & OBD change cat from failed to pass, and the fuel trims had went down to 0. But after a bit, went to -18, short term first and then now long term So, could this rich condition, also be due to clogged cat?
Hey, so being that you messed with the cat a bit and it changed it could be related. The engine needs to be able to efficiently exhale. If it can't it'll code. Yes, its plausible that a plugged cat could cause your issues.
Mike Becker, Senior Technical Instructor
@@GoTechTraining thank you.
NGK Technical Training thank you for your response, the injectors are new OEM,
Very informed video, a lot of doubts have been cleared. Your explanation are terrific.
Thanks for watching Mukesh!
Mike Becker, Senior Instructor
Very good video with a lot of helpful information . Thank you. Quick question, My car recently was running lean 21 percent lean long trim and 18 short trim on bank 2 due to a exhaust leak between the 2 flanges right before the cat. I got that fixed and now the car sometimes runs -18 but mostly stays on -6 to -12 range on short trim and bounces from -10 to 3 on long trim. How many driving cycles does it take for it to adjust to normal .So far I drove the car 3 times
Hey Jimmy, usually it happens pretty quick. Sometimes it's best to clear the fuel trims and drive with it fresh.
Mike Becker, Senior Instructor
My question about the Lambda reading on a scan tool is , for an example, 1.2 on your lambda chart on your video training, when you read this value on a scan tool , is the computer on your car taking fuel away because the fuel trims rich ? If someone can answer the question I would be thankful!
CEL TOO RICH TO LEAN AND MISFIRES.
I changed maf sensor n air filters. Light still on
Then Changed all Fuel injectors light still on.
Changed all spark plugs and all oxygens sensors light still popped back on.
What could this be please help! I’m tired of fixing stuff that probably wasn’t the answer. Last hope was the oxygen sensors once they were out they were fried bad . Once I clear the codes rev up and drive it handles fine. But once sitting idled it sputters
I've have learn a lot from watching this video thanks guys Just one question. My car was running lean on bank 2 due to a vacuum leak. 21 short term and 16 long term during idle Well I got that fixed and now its running rich each time I accelerate. Like sometimes 8- to 13- on the long trim and 5 to 8- on short trim. The fuel trims are okay during idle Is there anything I missed? or is it normal for the car to run very rich while accelerating it.
Did you figure it out?
I have a question i have a 2013 kia rio. LTFT is at +30 and STFT is 0. I checked for vacuum leaks and have none. Oxygen sensor reacts to fuel being sprayed into intake. I bypassed fuel system with terra clean machine and no change in trims. my question is could carbon on the intake valves cause this much fuel trim correction? this is a GDI engine.
I also wanted to add that raising the rpm while monitoring the fuel trims decreases the LTFT numbers down to about +20 and to me that indicates a vacuum leak, but no vacuum leak was found by spraying intake with brake clean. PCV is good too.
Christian, have you checked the air intake snorkel for tears? Also, how is the MAF sensor? The valves would need to be really bad to cause this extreme of a case. My feeling is that you have an improper measurement of air. Either not being read correctly or air sneaking in after the MAF.
Mike Becker, Senior Technical Instructor
Thanks for getting back to me Mike, this car doesn't have a MAF sensor it uses a Map sensor. I checked the Map sensor voltage and was sitting at 1.5v and I didn't see that as a problem.
At 33.12: it's not 260 seconds but 260 frames on the display of the snap on scanner.
Thanks for your time and effort.
Juergen, yes you're right. It is in frames not seconds, I misspoke. Sorry about that! Thanks for correcting it!
Mike Becker, Technical Services Instructor
I have 2010 impala with p0171, at first it starts fine but after running after 20 minutes the engine starts sputtering and dont go over 10mph. Im not sure what it could be. Any help?
I need y’all‘s help I have a 97 Toyota forerunner 3.4 L that I’m having a major Rich issue and every time I try something it does not work. I have replaced my O2 sensors, engine coolant temperature sensor, injectors, mass airflow sensor, fuel pressure sensor and about to change my fuel pressure regulator,fuel filter all vacuum lines as well as PCV valve, throttle position sensor. I got a new IAT but the vacuum tube on it fell off so I put the old one back on. I’ve done a compression test and all are within spec new spark plugs and coils and have swap the wires out with some wires that I had from before just to see if the ones that were on it are bad. The plugs are the dual tipped plugs that are recommended. There is a colder intake on the system which has been working fine on it for the past five years. All my fuses and relays check out yeT I am still getting a -20 something for my short term -17ish for my long-term. I get a misfire cylinder one error code but when I look at cylinder one misfire Count is less than 10 in the span of an hour. If I hit the throttle short term will zero out for a few seconds and then slowly Drop back to -20. When the engine is cool and I start it the mass air will be pulling close to 10 psi but after it Gets done with its warm-up cycle it drops down to around 3 sometimes even 2 1/2 psi. My injection it’s so low that the car almost stalls out somewhere in the upper 2gpm area. And when I first start the vehicle after it cooling down for a while it takes a long time to start. Somebody help me please
you are a very good teacher the best on the internet by far the way you explaine things im going to start to watch a lot of your content excellent
Hey Wackey, thanks for watching! I really appreciate the kind words.
~Mike
What if a a vehicle briefly goes to Open Loop - Drive on deceleration only till it stops? Truck is at normal operating temperature. But it stays in Closed Loop the remaining time.
2012 Toyota Tundra 5.7 240,000 miles
Any issues/codes? It may be base strategy to go into open loop during a fuel-cut decel.
Mike Becker, Senior Technical Instructor
GoTech there’s been no codes just intermittently being a startup at operating temperature where it goes straight to idle at 550rpm approx, most times it goes to like 900 and drops to idle which is normal. I’d also been noticing the mpg is getting lower. Idle began to become rough at stops randomly, not to a stall point. I looked at the maf it was dirty cleaned it and mpg got better then It began to tank. I could watch the fuel needle move as I drove say 50 miles and by 90 I consumed 1/4 tank, usually I’m about 120 miles for that.
I have had a scanner on it for a week as I drive watching fuel trims B1 LT is about 5.0 at idle and 2.7 as I drive, ST changes is quickly but is near 2 at idle and -0.8 some times near 1.5 as I drive .
B2 LT 3.0 at idle and nearly the same as B1 as I drive. ST is nearly 0 at idle and goes up to -2.0 as I drive. These numbers were far worse with the bad maf, pushing ST 10 on both banks and dropping to -1.0 as I drove. I’m still thinking that there’s a leak some where but the break cleaner test around the hoses and intake manifold showed no leak. My Evap canister was replaced, all new from Toyota. 10k miles ago.
Replaced the rattling gas cap as the fuel trim numbers got better, closer to 0 at idle B1 and B2 at idle hover between 0 and 3.7 at idle LT. Bank 1 tending to be the higher. And I eventually replaced the purge solenoid on the engine for not holding vacuum. And the numbers have been the same but are getting better, including the mpg. Maybe near 14mpg avg for my 150 mile day, as opposed to 11 or 12.
Sorry for the thesis here, but I’ve been analyzing this for a week now and it wasn’t till everything above was done that it did the OL- Drive thing. Maybe it’s a strategy like you say, a Toyota thing.
I have a p2098 bank 2 code on a Dodge Challenger 3.6L it’s running a lean fuel trim. What could my issue be? I’ve changed all O2 sensors and catalytic converters and still jerks a bit and had a check engine light. I added a fuel injector cleaner LUCAS and it removed my check engine light for 40 miles then it came back???
Eric, i'd start by monitoring the fuel trims. When does it run lean, idle, under load? This would then lead to the next steps, looking for vacuum leaks, fuel issues, etc.
Mike Becker, Senior Technical Instructor
Hi I need some help I have p1137 add fuel bank 1 rich. I have put all new parts to do with that code still comes up.
How do you check for a p1093?
I have bmw e46 it start ok but it not reving out what would cause that.
@6:11 and @7:46 I really don't see how an ignition misfire could trigger a po171 po174 (lean).
Great presentation Mike and looking forward to your lecture on the wide band sensors. Have a good weekend!
Thanks Stuzman! Glad you liked it, see you on the next one!
Mike Becker, Technical Services Instructor
Thank you guy’s for your patience and knowledge, where do I join classes? You guy’s should teach classes online or thrue zoom
P0171 basically means you have a vacuum leak usually the first place I go to the gas cap to make sure it was tightened properly because if it is not then you're going to show a vacuum leak.
Hey David, thanks for watching. So a vacuum leak can set a P0171 but there's also a ton of other things. Also, the gas cap is more likely to set an EVAP code like P0440 or something before setting a lean code.
Mike Becker, Senior Instructor
Ummm no , not correct at all
@@icepick859 yes is correct
@@BillNye-bj5vi Yeah okay, gas cap going to set p0171. uh huh
I've got a Ford Focus 1.6 petrol 2006 mark 2. It's long term fuel is minus 10. It's long term negative numbers have been slowly been going more and more negative. There is no engine light on and seems to run OK. Where do you suggest looking? Thanks :)
John, when your trims are going negative that means your engine is running rich. Verify fuel pressure first off. See if you can force the engine lean to see if the O2 is responding.
Mike Becker, Senior Technical Instructor
@@GoTechTraining how do you see that?
if you force off and 02 is not responding what will be the culprit here?
My 2010 Chevy malibu I have the po172 code engine will nit start the oil has gas in it the MAP sensor checked out ok any ideas that would make bank 1 rich
Okay after watching the this video training my question was answered! Great training thanks!
Thanks for detailed explanations. I appreciate all work you put into making this video.
Hey PistonShack, thanks for watching! :)
Mike Becker, Senior Instructor
Very useful information sir thank you
Sir I have Chevy suburban 2007 and I'm getting codes p0172 and p0175 system too rich on both banks and ratio is showing short fuel trim at 0 and long fuel trim at -25 what do you suggest me to do first
Thank you for watching A Rahman! On your suburban, these were very common to run into fuel composition calculation issues. There should be a PID on your scanner saying ethanol content. Verify that seems right. if you are running standard pump gas we usually look for 5-10%. Anything higher than that can give you issues. Ethanol requires higher fuel volume which could be exactly why your truck is running rich.
Mike Becker, Senior Technical Instructor
Very informative. Thanks for the taking the time. You teach a great class. Your step by step process is unmatched. Thanks for passing the knowledge to us all.
A RAHMAN fuel pressure regulator.
Dona fuel pressure leak down test. Must hold 55psi for several minutes after key off.
great info!! hard to follow with the difference in time between video and audio!!
What about a failed spark plug boot or leak in hose to evac.
Better than tele. Keep up the good work. Stft and ltft no longer a mystery. Thanks.
Hey Jesse! Thanks, best part is that it's free unlike cable :) Thanks for watching!
Mike Becker, Technical Services Instructor
I have a Lexus is350 showing p2238, I have replaced the O2 sensor the dtc does not go away. After checking the fuel trims I have 0 on both on short fuel trim but on the long fuel trims they are -3 and -6, any idea about what is causing it?
Hey Robertoyzayda, you're fuel trims seems pretty normal. Could maybe just be a bad sensor?
Mike Becker, Senior Technical Instructor
Plz help me.... Don't understand trim but help... My k20 civic si... Burn rich but no code ... Run poor and but runs better when low on fuel... I cleaned maf and map senors and throttle body and nothing help plz.... Also when the car is real cold it starts at a low idle then jumps to below 2000 rpm
You have to find what's causing it to run rich. Are you able to force the car lean? Is the purge solenoid stuck open all the time?
Mike Becker, Senior Technical Instructor
@@GoTechTraining what's the purge solenoid.... I am sorry I Jus trying every thing..... Gonna try and clean the pvc valve and the air assist control valve... Maybe it's not getting enough air....?? But the air to fuel is jus all over the place
The Purge solenoid is the solenoid that connects eventually to the vapor canister. Your best bet on here may be to take this thing into a shop for a diagnosis.
Mike Becker, Senior Technical Instructor
@@GoTechTraining did..... But realise u gave me the best idea than any other mechanic here.... These problems I am having more seem to be as u say the evap system or the canister.... Gonna take them down and check them... But how can I test the solenoid or jus get a new one????? Please and thank you... U have been a great help
Question
I replaced the intake manifold gasket and Throttlebody gasket and replaced the egr valve and evap and still getting a lean code what can it be
Have you checked fuel pressure? maybe it's low? Maybe there's water in the tank?
Mike Becker, Senior Technical Instructor
Do you have any videos that go over closed loop fault? I have a 03 Ford expedition that is stuck in cl fault. I don't know how to approach this issue
Robert, closed loop fault is the vehicle not able to obtain closed loop. Do you have any trouble codes?
Mike Becker, Senior Technical Instructor
I have 2004 mini cooper 1.6l r50
check engine light on and code p2097 post catalyst fuel trim system too rich bank1 what should I do? somebody said I should change a oxygen sensor... but which one should I one on the hood or one under bottom of the car?
P304 code & P0174. Have 2009 Ford escape 3.0l. How does the miss fire possibly cause my lean code?
I have a 1996 F250 5.8. It only has 116k miles on it and the engine sounded really good until a few weeks ago when I put about 2 year old gas in it. I KNOW THAT WAS STUPID. it was about 10 gallons. The very next day, it was rough starting up but it ran fine once it started, however, the next day, the truck was shaking, started sounding like it was misfiring, and whatever. I didnt siphon out the bad gas, instead I out fresh gas in.
The fixes I have done on it thus far are: fuel filter, cleaned injectors, spark plugs and wires, new distributor cap and rotor. and it still isnt running right. I took it to a DIY mechanic who has been a mechanic for probably 50 years and he said it sounds like the lifters. What do you make of it?
Do you think that the gas is a coincidence? I find it hard to believe adding old gas caused it to ruin lifters that were fine before. I don't buy it. I would inspect fuel trims. Maybe your gas had water in it and the truck is running lean to the point of misfiring. Not sure on that lifter idea man. I'd do some testing before jumping to engine work on a truck that sounded good.
Mike Becker, Senior Technical Instructor
I didnt think so either. My dad had said he didnt believe old gas would be the culprit, but the water content may have the engine running lean. Thank you so much. Ill take this info and work accordingly. You the man. SUBSCRIBED!
Old gas can cause an engine to run poorly. You could try adding some of that water eliminator to the tank. See if it helps, it shouldn't hurt anything. Thanks for subbing man!
Mike Becker, Senior Technical Instructor
I got a 08 Hyundai Accent with. P2096 code. Changed both upstream and downstream oxygen sensors and I still get the code back......any suggestions?
Eric, that P2096 is a lean code of sorts. You need to inspect the vehicle for a lean condition. Maybe it has something to do with an air leak before the post cat o2 sensor.
Mike Becker, Senior Technical Instructor
I have a 2002 Dodge Neon SE, P0172 code with 160,000 miles. No vacuum leaks, new plugs, new map sensor, new IAC, new O2, and new injectors. Still have the code after reset. Can you guys help? I`m ready to push my daily driver off a cliff. Fuel trims are pegged at -25. codes were reset after each part was replaced. Car will not pass Pa. inspection with MIL on.
I just replaced fuel injectors for 2004 prius, after two weeks check engine po172. Appears. Please help.
Is the maf used in closed loop aswel as open loop?
Hey Solar, thanks for watching! Yes, MAF is used in both, typically.
Mike Becker, Senior Instructor
@@GoTechTraining ive another question what would throw a vvt code on an ls1 gen 3 that doesnt have vvt?
What code are you seeing? And whats the y/m/m?
Mike Becker, Senior Instructor
@@GoTechTraining sorry wrong code comes up MPI VT-SAE and GS 2.0-VT for a 2005 holden VZ SSZ
My car is a 02 chevy prizim. I keep getting a po 420 cat system low efficiency code.
I have already replaced the following. The upper and lower purge solenoid was replaced, Replaced the charcoal canister, changed the up and down stream 02 sensor. I replaced the mass air flow sensor. I replaced the cat. I also checked all the evap hoses and their is no leaks. I also changed all the spark plugs and pick up coils.
I'm at my witts end and trying to figure out. Why it keeps giving this code. And keep blowing the cat, purge solenoids and pick up coil.
I also did a smoke test and it well sealed.
Hi great lesson, my LTFT is at 0% since I checked a few months ago, does that mean my trims are really good? my STFT go's from -6% to +6 and bounces up and down between the two .
is that a good thing ?
Hey 337 Thanks. Yeh that sounds good. Your short terms will bounce, that's normal. +/- 6 sounds pretty average. Long terms at 0 is what's really nice. Means the car seems to be dialed in!
Mike Becker, Technical Services Instructor
Wells Vehicle Electronics thanks for the reply, 20 year old honda civic b16a sir2 engine, stock , I'm happy with that answer just shows how well made them engines are.
Thanks for the reply and love your videos.
Long Term is the window of time the adaptive memory dictates the fuel trim, Short Term is live data calculating to learn the parameters for the adaptive memory to update the Long Term. The O2 sensor signals lean below .45 volts & rich above .45. The Engine Controller only cares about that threshold & uses that to determine fuel trim. .. in other words the computer calculates the % of time that the O2 sensor is past the threshold of .45 volts & does that each time the threshold is crossed.
Hey, thanks for the video. Very helpful. My shogun sport v6 has codes P0170 and P0173, both fuel trims. It seems to be running fine except a slight change in idling speed every minute or so (from 1000 to 700ish RPM). The previous owner has changed an o2 sensor (top of cat) but the 'check engine light' is back on. I've unplugged the MAF sensor and the idling speed increases, then goes back to normal once plugged back in. That's all I've done so far.
Any ideas appreciated! Bit of a head scratcher 🤔
Hey Mark, Do you have a scan tool that can watch data? I'd like to see what the fuel trims are reading at idle and at a moderate load. There are a lot of possibilities to what could cause this issue.
Mike Becker, Senior Technical Instructor
@@GoTechTraining thanks Mike, yes I have the torque light obd2 thing I'll take some screenshots and send them to you if you like? There's 4 sensors per bank, I'll try and get them on the same screen. What's your email?
Sure, send them to MCBecker@NGKSPARKPLUGS.com
@@GoTechTraining emailed you 👍
So I'm so confused 2005 PT cruiser replaced 2 02 sensor P0031 and P0037 OH2S) both low voltage ( FL0007 EE18 BL01 threw this at one point as well but I think it's cleared couldn't find what this meant) people are telling me that mean it's running lean so it's a vacuum leak... I'm freaking I tried replacing the PCV valve thinking it may be clogged... still save codes could a leak in the exhaust be ducking sir all is brand new but I'm wondering it the bolts aren't tightened enough the guy that was under there last had an issue tightening a bolt. I've been up 2 weeks solid 3 in the morning trying to learn and figure it out!
Kathy, if both 02 sensors are reading low voltage and they've been replaced then you have only a few things it could be. Could be air leaks in the exhaust before the sensors, a severely lean running engine, a wiring issue from 02 to PCM or a PCM issue. My next test would involve feeding the engine some sort of fuel, probably propane, to see if I could get the 02 sensors to show rich. This tells me the sensor works, the wiring is ok, and the PCM is ok. if I richen the engine and I get no reaction in the data...then I have a sensor, wiring, or PCM issue. That make sense?
Mike Becker, Senior Technical Instructor
@@GoTechTraining Thank you so much I've Been telling the mechanics around here that but they look at me like I have 4 heads I have to find someone that can understand this concept because I don't have a heck of alot of testing equipment. ...it's hard in the Albany, NY area. I understand it could also be an oil leak it the Oil pressure switch is leaking it could act like a vacuum leak as well s this correct? Or a purge Solenoid I already replaced the PCV valve. Thank you so much I greatly appreciate it !
Kathy, not sure how an oil pressure switch could cause this issue. A bad purge solenoid could though if it were stuck wide open.
Mike Becker, Senior Technical Instructor
@@GoTechTraining I just read somewhere how touch the system is if something is working incorrectly sends a signal back to CPU (EPC or EMC) it will reduce voltage how crazy they made it this sensitive
KATHY.. i have a software and scanner let me know what you need
Can y'all do some post carb, pre obd2 fuel trim videos PLEASE!? Reading blinking lights sucks! Do u have insight?
My issue on a poor random idling 92 Nissan MT KA24E KC XE no CEL per Nissan. I'm sick of it becoming this parts cannon.. still have all original parts on hand.
So I got a po191, po171, po174..I replaced MAF, Throttle body, fuel rail sensor and fuel pump module on my 2005 f150 v8 3v...what is the solution. I have loss of power under load ...I am tired of throwing. MONEY at it...
Fantastic lecture!
A connected topic: anybody knows how to deactivate learning procedure on a flex fuelcar (volvo in this case) . Thre is no ethanol content sensor but computer leatns thru the Lambda readings and injection pulse duration ...causing many problems when driving regular fuel. I am tired iwth them so simply would love to deactivate the process but there is no obvious way to do so. I can only reset the content to the default value of 50%. Then the crap learns and sometimes rich 70% with the engine to be floode on a cold start.
Ideas?
Thank you very much! That seems crazy that the car would "learn" such a high ethanol count with no ethanol in the fuel..what's it truly learning? Are you sure you don't have something wrong causing it to read so rich? I've seem the algorithms get stuck, GM especially, but after resetting they are usually ok again. Is there maybe a software re-flash for the car or something?
Mike Becker, Senior Technical Instructor
@@GoTechTraining I missed your reply! Thanks.
There is a counter for ethanol content and each time you fill the tank the learning algorithm is initiated. It learns thru the lambda and injections timing. Therefore if there is something wrong with with fuel to sir ratio it interprets it as alternate fuel percentage in the tank and store ty he ethanol content reading. Next time you want to start in cold conditions it ask long injection time to account for ethanol and the engine is flooded.
And I have a bi-directional tool so I am able to reset the content to the default (50% !) value.
So yes, apparently there is something wrong but it is do tough to find out with this intelligence involved 😂.
Would love to deactivate it first but have no idea how. Thinking about replacing the ECU for similar engine one but not accommodated as the flex fuel.
Hi can someone answer my question I have 07 ford f150 5.4 it has 171 code I put mass sensor and02 sensor on but it read long term 99.2 bank 1 sensor2 please help
You may have a vacuum leak, some times you can hear the leak. If you can't find it you may need to smoke your engine to find it. ALSO Exhaust leak before o2sensors 1. Good luck I'm sure you will fix it 😊
Thank you so much for taking the time to explain everything!!
Hey J G, thanks for taking the time to watch and comment!
Mike Becker, Senior Technical Instructor
I have a p0172 code, running rich. Only went on when there was a cold snap and engine light went off when weather warmed up. By cold I mean -30c then warming to -6c. Could a sensor freeze?
Hello I own a 2005 Crossfire I have codes Chrysler with code P0172 and P0175 > I have had problems I also code P0239 Air induction blower failed but I hear it running at start up. I am a senior citizen and can't afford to take it to a shop if I could find one my next thing is take it off the rd Most shops do not want to work on this car since it is a Bastard car neither Mercedes or Chrysler or individual shops will not touch this car. It has a Mercedes engine 3.2 Liter V6 . I replaced all injectors and plugs wires and and individual coils the car runs great but as soon as I get close to the emission station it throws the P0172 and P0175. I looked for loose vacume hoses and I found one and I fixed that. My car is due in February and I don't know what I can do get this to pass emission. In a few years the car is exempt emission if I use Historic tags. I don't drive car much but the emissions will not allow me to go through the test for a week. Like I said the car runs great but soon as I get close to emission station it throws codes. I drove it for a week and today it did same thing 3 times in a row I went to the emission station. How frustrating.
hi, i,m new subscriber, great video! my car is nissan skyline 300gt 2002 year. lambda is 1,017, but CO is very high 1,57-1,76. what is possible causes? thanks!
Absolutely Brilliant!!! Thanks for the Detailed Explanation!
If a fuel pressure regulator is bad, will it always leak? Or can it still be bad and not leak?
Hey M.Night207, what kind of pressure regulator are we talking about? The old school vacuum diaphragm one? If that's the one, then ya, generally speaking it will be leaking if it fails.
Mike Becker, Senior Technical Instructor
please help what are the most common cause of PO103 code on the vw passat I thank you
What year Passat and what engine are we working with here?
Mike Becker, Senior Technical Instructor
@@GoTechTraining004 passat 2.8l 4motion
I got a question so I have a 2003 Ford Mustang 3.8 v6 and my LTFT B1 and B2 are both at -99.5 but no codes at all and engine seems to be running fine what’s going on with it?
How about a pO170 code? Does this video also apply to this code?
My car is LTFT -10.3 ? but everything like 02 doing as it should thorts pls
Hey KComputers, curious, what are you STFT when the LTFT is -10.3? Are they hovering 0? A -10 trim shows you are running slightly rich. What kind of car is this on?
Mike Becker, Senior Technical Instructor
to anyone watching this in the future and notices the audio is off, a way to get around this is 2 have two youtube tabs open of this video, one to watch on mute, and another to have audio playing and minimized. the time difference is ~9:40 seconds. so fast forward one to that time mark and then hit play on both of them as quickly as you can. was driving me crazy.
So if my 03 Toyota Corolla S is giving me P0420 and p0446 and p0440 and p0171. Should I replace both o2. The car has like 350000 miles lol so I’m guessing everything is old or shot and needs to be replace... thank u
Hey Mike, I'm 52 years old and knows nothing about the tech side of a car...been watching your videos, if I don't understand I'll rewind for second and third viewing, but I'm learning so much from you. Just brought a scanner (Autel MOT Pro, is this good scanner?) and playing with it and understanding it more because of your teachings....you are doing a great job, minus the cough. If I could give you 10 thumbs up I would.
Hey John, yeh i was a little bit sick in this video. Glad we are helping you learn. Means a lot to us! That's a good starter tool. Get's you some codes, and some info. There will always be room to grow in tools if you really get into this. Thanks for watching!
Mike Becker, Technical Services Instructor
I have a car that can run on petrol and on LPG. When run on petrol I get HO2S 0.3V, stuck lean. When run on LPG, I get HO2S 0.7V stuck rich.
Also HO2S is brand new and OEM. Using OBD reader,HO2S voltage is constant, it is not moving from rich to lean.
Any idea what to look for?
5 Cracks in the exhaust manifold will that make it run rich?
Manifold issues could definitely cause a vehicle to change the fuel trims. If the cracks are drawing air in then I would expect the engine to go lean, not rich.
Mike Becker, Senior Technical Instructor
if the system showed lean then it would call for more fuel correct?
Vcoldduck you would have positive fuel trims
so if my 97 ram 1500 5,9L came with 1 pin hole injectors and i upgrade to 4pin hole injectors im gonna be running richer but if the PCM can trim enough like 12-15% negative i should be okay and no CEL?
Hey Joey, if you're changing the flow rate of the injectors you'll need to program the PCM. It will likely set a code and not properly fuel.
Mike Becker, Senior Instructor
@@GoTechTraining What if I can't program the pcm? Is there another way to adjust the pulse width on the injectors?
Very informative video. I have a p0301 and my car have a rough idle after a warm up. During the initial rough idle when the car start I notice my STFTspike up to -20% and LTFT 0% and go back to normal. My car also hesitates or loses power between 2.5k to 3k rpm. What you think the possible issue ?
Hi Wendy, honestly there could be 1000 different things causing your issue. Your P0301 means your computer is recording misfires on cylinder 1. The misfire could be causing the fuel trim spike, or the fuel trim spike could be causing the misfire. What kind of car, miles, maintenance record? Need a lot more information to be able to get you any sort of accurate idea.Thanks!
Mike Becker, Technical Services Instructor
Wells Vehicle Electronics Im driving a Subaru 07 wrx turbo 160k miles. Car has always been stock and no modifications other than cold air intake ( never have any issues after installation). I've replaced from spark plugs and coils. New OEM o2 and maf sensor replaced due to needed for placement. For the maintenance and condition of this car I have always service myself. I like to do preventative maintenance so everything up to par. Now I'm stump where I should look. Thank you.
Wendy, sounds like you really enjoy keeping your car nice. So, it seems you have replaced many parts already that I would have suggested at maintenance. That's good! So we have 2 clues here, P0301 and a rich condition at initial starting of the car. I would put a fuel pressure gauge on it at this point. Monitor the pressure when the key is turned off. It should hold. I am thinking you have a partially stuck open injector that is leaking fuel into the cylinder. This can cause a rough idle that clears up. Also, have you been adding coolant at all? These motors are known for head gasket issues, is it possible your engine's leaking coolant into cylinder 1 when it sits, then burns it off at start up? Does cylinder 1's spark plug look different than the other 4?
Mike Becker, Technical Services Instructor
Wells Vehicle Electronics, the spark plugs have similar wear nothing noticeable difference. I gapped the spark plugs to specs at .030. I swap the coils and spark plugs and also the injectors between cylinder 1 and 4. I did a fuel injector clean individually by modifying a spray carb and choke cleaner with a 9 volt battery. And the spray seem to be fine with similar stream. There are no after leaks after the spray. I'm changing the o ring for all the injectors since I notice slight deterioration. But I have not test the fuel pressure since I don't have the tester. How is it possible that I have a vacuum leak by seeing short term fuel trim and long fuel trim ? And also my 02 sensor for bank one is 2.9 volts and fluctuated between 2.8 with very little voltage variation ( this before the cat converter.) but my post cat converter fluctuate between 200mV and 800mV. My car symptom is rough idle at warm up, and my car also hesitates at 2.5k rpm in every gears. With my pedal to the floor my car won't pick up speed until the rpm slowly pass 2.5k rpm.
Your fuel trims are showing a rich condition. The fact that your short terms go negative means the PCM is taking fuel away, not adding like it would for a vacuum leak. The front sensor on there is probably a wideband a/f ratio sensor. The voltage will probably sit right around there. Watch our wideband class, I go in depth into them in there. You have done all the checks I can suggest over the internet. At this point I would want to look at live data on a scan tool and see if anything sticks out. It may be time to find a really good diagnostic shop and take it there :(
Mike Becker, Technical Services Instructor